Process for making laminated glass



Patented Nov. 1, 1932 UNITED STATES.

PATENT cal-"Ice.

O. LYTLE, OF NEW KENSINGTON, PENNSYLVANIA, ASSIGNOR. DUPLATE CORPORATION, A CORPORATION OF DELAWARE PROCESS FOR MAKING LAMINATED GLASS No Drawing.

The invention relates to a process of making laminated glass and involves a development of the process set forth in the patent of J. H. Sherts and R. E. Hamill, No. 1,781,084. In such process two pressing operations are involved; the first, a preliminary operation, I

in which the sandwich consisting of two sheets of lass and an interposed sheet of cellulose pIastic, or other material such as celluloid or resin, are secured together by cement or other suitable means so as to seal the joints at the edges of the sheets; and the second, a final pressing OPBI'tLtlOIl, 111 which the laminated plate is placed in a bath of liquid and heat and pressure applied to complete the laminating process. In such Sherts and Hamill operation, the liquid emtplo iged in the final pressing operation pre era ly consisted of a solvent for the plastic, and one of the main objects was to avoid any necessity of the so-called edge sealing, such sealing comprising an operation well known in the art, involving the grooving out of the celluloid around the periphery of the plate to provide a space for pitch or other suitable sealing materlal.

The present invention contemplates a modification of the Sherts and Hamill process, in such manner that the edges of the laminated plates are grooved for sealing (or for another purpose) coincident with the final pressing operation. To that end, a corrosive liquid, such as concentrated sulphuric acid is substituted for the solvent of the Sherts and Hamill process. During the final pressing operation, this acid attacks the plastic sheet at its edges andremoves it to the depth desired for sealing, reaction products being formed which escape (gas) or are readily washed out after the completion of the final pressing operation. The use of the acid involves ad'esirable improvement, even when the plates are not to be edge sealed, as the grooving out of the celluloid,makes the edging operation, in which the edges of the plates are ground on abrasive wheels, much easier. Ordinarily much trouble is encountered in the grinding of the edges of laminated plates due to the celluloid gumming up the grinding wheels, and the grooving out of Application filed October 10, 1931. Serial No. 568,201.

grees F., and the pressure in the tank raised to about 150 pounds per square inch, the apparatus and procedure being similar to that set forth in the Sherts and Hamill patent.

These conditions are maintained for 5 to 10 minutes, after which the pressure is released,

the tank is opened and the plates are removed and placed in a bath of hot water to Wash out the remainin products formed by the reaction of the su phuric acid with the edges of the plastic sheet. described produces a satisfactory lamination with an edge groove about one-eighth inch in depth.

The depth of the groove secured ma be regulated by the period in which the p ates are subject to pressure, by the concentration of the acid, and its temperature in the auto clave. Such groove is somewhat deeper when the plates are edge sealed than when edge sealingis omitted. The sulphuric acid preferably employed isofstandard or commercial concentration; namely, about 95 er cent. The rack employed for carryin tie plates when they are placed in the autoc lave is preferably arranged so that the lates be horizontal instead of vertical, as is the case in the Sherts and Hamill apparatus of said patent.

Other acids may be substituted for the sulphuric, the most available being hydrochloric acid having a concentration of 95 per ccnt. A solution of caustic soda may also be used instead of the acids to react with the plastic. The pressing operation, might also, under certain conditions and with certain cements, be carried on without the application of heat, although the action of the corrosive fluid, in such case, is necessarily slower.

In addition to the advantage of accomplishing the two functions of pressing and edge grooving in one step, this proce ss offers The procedure above 2' v p I neonate the advantage of delivering the'glass clean a on rinsing; of eatly reducing the cost o' the pressing so ution, as compared with diethyl glycol "mono ethyl ether or dihutyl phthalate referred to in the Shorts and Hamill patent and of avoiding any fire hazard,

What ll claim is: l. A. process of laminating glass and rein m forcing sheets of organic material, which consists in prelinar ly cementing such sheets together, so as to seal the joints at the edges of the sheets, submerging the composite plate thus formed in a bath of corro- 15 sive fluid which will react With the material of the reinforcing sheet to term reaction products and remove he edges of the reinforcing sheet to a point inside the edges of the glass sheets, and applying pressure to :a the loath to complete the lamination the sheet,

2. A. process of laminating; glass and cellu lose plastic reinforcing sheets, which con-- sists in preliminarily cementing such sheets 23 together, so as to seal the joints at the edges of the sheets, suhmerging the composite plate thus formed in a hath of corrosive fluid which Will react with the material of the reinforc ing sheet to form reaction products and re- 30 movethe edges of the plastic sheet to a point inside the edges of the glass sheets, and applying pressure to the bath to complete the lamination ot the sheets.

3. A process of laminating; glass and cellu- 33 lose plastic reinforcing sheets, which consists in preliminarily cementing such sheets together, so as to seal the joints at the edges of the sheets, suhmerging the composite plate thus formed. in a bath of hot concentrated g; acid which will react with the material of the reinforcing sheet to form reaction products and remove the edges of the plastic sheet to a point inside the edges ofthe glass sheets, and applying pressure to the bath to com- 4.? plete the lamination of the sheets.

4. A process of laminating glass and cellulose plastic reinforcing sheets, which consists in preliminarily cementing such sheets together, so as to seal the joints at the edges :3 of the sheets, exposing the plate to hot concentrated acid under pressure sufficient to complete the lamination of the sheets, which liquid contacts with the surfaces of the plates throughout including the joints at the edges of such plates, nlaintalningthe plate in the liquid'until such acid removes the edges of the plastic sheet to a point inside the edges 7 of the glass sheets, and then removing the plates from the bath and washing away the C3 remaining products formed by the reaction between the liquid and the plastic.

In testimony whereof, I have hereunto subscribed my name this 21st day of September,1Q31. r WILLIAM o. LYTLE. 

